Governments around the world are beginning to take action on a newly recognized climate threat that has been right in front of our eyes for decades: the soot that spews from diesel engines and that forms hazy blankets over villages using wood- and dung-burning cook-stoves and areas where forests have been cleared by burning.
Soot, or black carbon, is believed to be responsible for 18 percent of the planet's warming, an impact that wasn't well understood just two years ago when the Intergovernmental Panel on Climate Change released its latest report.
"Black carbon is now commonly believed to be the second most important climate forcing agent after carbon dioxide," says Erika Rosenthal, an international program attorney for Earthjustice.
At a meeting of the Arctic Council today in Norway, the United States, Russia, Canada and other Arctic nations took the first step to begin reducing that danger by establishing a task force that will examine ways to decrease the global production of soot.
In the United States, an unlikely coalition of U.S. senators – including both Barbara Boxer (D-Calif.) and chief climate change denier James Inhofe (R-Okla.) – recently introduced a bill to similarly look into ways to curtail black carbon emissions. The U.S. stimulus package also contained money to decrease soot, and other projects in Europe and developing countries around the world have begun to address the problem.
Wind currents carry soot from North America, Europe and Asia to the Arctic region, where the particles darken the ice and absorb heat. The melting of the Arctic carries multiple climate dangers, from rising sea levels to the release of greenhouses gases such as methane frozen in the permafrost.
The task force will recommend actions to be taken and will report to the council, which is composed of Canada, Denmark, Greenland, Finland, Iceland, Norway, Sweden, Russia and the United States, at their next meeting in 2011.
The Boxer-Inhofe bill in the U.S. Senate would give a similar task to the EPA: In the next year, define black carbon, find its sources and ways to reduce it, and determine funding for such solutions. (Inhofe's support was prompted by the health dangers tied to soot.)
One key to begin solving the problem of black carbon in the Arctic is developing standards for the diesel engines of marine ships the enter the area, Rosenthal says. Last month, the EPA applied to the International Maritime Organization to establish standards for all international ships that enter U.S. territorial areas. However, it did not include the Arctic waters.
"We hope they change that," Rosenthal says. "The IMO is set to discuss particulate standards for diesel engines in its next meeting this summer, and it will be really important to include the American Arctic in that missions control area designation so we can enforce reductions on all international ships in our waters."
The U.S. took a step forward with the $300 million set aside in the stimulus package for cutting black carbon from diesel engines. The Diesel Emissions Reduction Act funds diesel particle traps that capture black carbon from the engines. Diesel engines, accounting for 50 percent of our black carbon emissions, are regulated under the Clean Air Act, but rules adopted in recent years only apply to new vehicles.
The advantage of taking swift action on soot is that it will have a quick impact on the climate compared to efforts to reduce carbon dioxide and other greenhouse gases. Black carbon only stays in the atmosphere for a few days or weeks, whereas other greenhouse gases stay for a hundred years or more.
Swift action could also help prevent or at least forestall downward spirals known as feedback loops, several of which are possible in the Arctic. For example, warming temperatures cause ice to melt, which means there is less ice to reflect sunlight away from the Earth and more exposed, dark ocean to absorb the heat, which causes more warming, which melts more ice, and so on.
The same cycle happens with the permafrost, which releases methane, a potent greenhouse gas. Many scientists are already seeing these feedback loops in action. Cutting black carbon emissions might buy more time to tackle greenhouse gases like carbon dioxide.
"We need to buy time for the Arctic so it doesn't melt," says Rosenthal. "We need to buy time so the world can implement the Copenhagen deal" – the December United Nations Climate Change Conference in Denmark, where the follow-up international agreement to the Kyoto Protocol will be negotiated – "and a leading strategy to do that is to address the short forcers, particularly black carbon."
Drew Shindell, co-author of the study of black carbon in the Arctic and a climate scientist at the NASA Goddard Institute for Space Studies, says black carbon has caused anywhere from half to one and a half degrees Celsius of warming in the Arctic since 1890; total warming was almost two degrees.
"Over the next 20 years or so, carbon dioxide will continue to increase. So even if you get a one-degree cooling from the black carbon, you're still going to have to deal with warming from CO2. But relative to what the temperature would be if you didn't do anything about black carbon, you could have a really big impact."